The continuous polymerization of anionic polymers using radicals has already been described in application US 2014/0088280.
In this application, the inventors have sought to develop a method allowing the production of anionic polymers in solution with a defined, very narrow molar distribution by mass, which is energy saving, that is to say without preheating, with a reduced risk of clogging in the micromixer and/or the reactor and/or, as much as possible, making it possible to avoid corrosion problems in the case of the use of monomers containing acid groups.
The inventors have thus proposed the use of microreactors having an internal diameter of less than 30 mm. Their method requires several mixes upstream of the microreactor and a microreactor per polymerization area.
However, there is a constant search for methods which allow the continuous polymerization of polymerizable anionic monomers using radicals, the polymerization reaction of which is particularly exothermic and rapid, thereby generating numerous technical and safety problems. Mention will in particular be made of acrylic acid, which is an extremely reactive monomer. It is in particular for this reason that, from an industrial point of view, it is still at the current time preferred to use semi-batch methods which however create relatively long cycle times.
In addition, to the inventors' knowledge, in the continuous reactors proposed to date, problems of formation of plugs which block the reactors, due to the formation of gels during the polymerization, are encountered. In addition, the degrees of conversion are often low and can require additional treatments.